Warning sign



FIG. 1 is a perspective view of a warning sign showing my new design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top plan view thereof; and,

FIG. 7 is a bottom plan view thereof.

In the drawings, the broken lines depict environmental subject matter only and form no part of the claimed design. 

CLAIM The ornamental design for a warning sign, as shown and described. 